The present invention relates to a tool for peeling a turntable polishing cloth used to peel a polishing cloth adhered to a turntable of a polishing apparatus.
In the manufacture of semi-conductor wafers, a polishing apparatus has been used for polishing semiconductor wafers so as to enable a surface of a semiconductor wafer to be made flat with a mirror-surface finish.
FIG. 8 is a schematic sectional view of the polishing apparatus 100. As shown in FIG. 8, such a polishing apparatus comprises a turntable 95 and top ring 213 which are rotated respective numbers of rotations, and a surface of a semiconductor wafer 220 held by the top ring 213 is contacted with a surface (polishing surface) of a polishing cloth 80 adhered to the turntable and polished while abrasive liquid from an abrasive liquid supply source.
In more detail, a top ring head 210 is disposed above the turntable 95 and includes the top ring 213 for pressing the semiconductor wafer 220 against the turntable 95 while holding the semiconductor wafer. The turntable 95 is connected to a motor (not shown) to be rotated around an axis 96 in a direction shown by the arrow R. The polishing cloth 80 is adhered to a top surface of the turntable 95.
The top ring 213 is connected to a motor and a lift/lower cylinder (not shown). With this arrangement, the top ring 213 can be lifted and lowered as shown by the arrow S and can be rotated around its axis as shown by the arrow T so that the semiconductor wafer 220 can be pressed against the polishing cloth 80 with any pressure. The semiconductor wafer 220 can be sucked to a lower surface of the top ring 213 by vacuum or the like. A guide ring 216 is attached to a lower peripheral portion of the top ring 213 to prevent disengagement of the semiconductor wafer 220 from the top ring.
An abrasive liquid supplying nozzle 215 is disposed above the turntable 95 so that polishing abrasive liquid can be supplied from the abrasive liquid supplying nozzle 215 to the polishing cloth 80 adhered to the turntable 95.
A dressing head 211 includes a dressing member 218. The dressing member 218 is diametrically opposed to the top ring 213 above the polishing cloth 80 so that dressing of the polishing cloth 80 can be effected. A water supplying nozzle 221 can supply a dressing liquid (for example, water) to the polishing cloth 80 on the turntable 95. The dressing member 218 is connected to a lift/lower cylinder and a rotating motor so that the dressing member can be lifted and lowered as shown by the arrow U and can be rotated around its axis as shown by the arrow V.
The dressing member 218 is constituted by a disc having a diameter substantially same as that of the top ring 213 and is provided at its lower surface with a dressing tool 219. The abrasive liquid supplying nozzle 215 and the water supplying nozzle 221 extend up to the vicinity of a rotational center of the turntable to supply the abrasive liquid and the water to predetermined positions on the polishing cloth 80, respectively.
By pressing the semiconductor wafer 220 held by the top ring 213 against the polishing cloth 80 and by rotating the turntable 95 and the top ring 213, the lower surface (to be polished) of the semiconductor wafer 220 is rubbed against the polishing cloth 80. At the same time, by supplying the abrasive liquid onto the polishing cloth 80 from the abrasive liquid supplying nozzle 215, the polished surface of the semiconductor wafer 220 is polished by the combination of the mechanical polishing action of the abrasive particles in the abrasive liquid and the chemical polishing action of alkali (liquid component) in the abrasive liquid.
When the semiconductor wafer 220 is polished by a predetermined amount, the polishing operation is finished. At this point, since the polishing cloth is worn by the polishing action, thus causing a deterioration in polishing ability, dressing of the polishing cloth is effected.
That is to say, in a condition that the dressing member 218 holding the dressing tool 219 and the turntable 95 are rotated, the dressing tool 219 is pressed against the polishing cloth 80 with predetermined pressure. In this case, the water is supplied onto the polishing cloth 80 from the water supplying nozzle 221. By supplying the water, the waste abrasive liquid remaining on the polishing cloth 80 is washed out, thereby refreshing the polishing cloth.
When the semiconductor wafer is polished by the polishing cloth, since the polishing cloth must not be peeled from the turntable, the polishing cloth is firmly adhered to the turntable. Thus, when the worn polishing cloth is changed to a new polishing cloth, a strong force is required for peeling the worn polishing cloth.
In the conventional technique, in order to peel the polishing cloth, as shown in FIG. 5, the operator enters into the polishing apparatus 100 by the upper half of his body, and, a part of a peripheral edge of the polishing cloth 80 is caused to be slightly peeled from the turntable 95 and the polishing cloth 80 is pulled forwardly (toward the operator) while pinching the peeled part of the polishing cloth by means of pincers or a pliers 110.
However, in this peeling method, not only is a strong force required to peel the polishing cloth, but also, if the pincers or pliers 110 are disengaged from the polishing cloth 80 during the peeling operation, the operator may be injured by being struck against the ceiling or any internal structure of the polishing apparatus 100.
In order to avoid such inconvenience, as shown in FIG. 6, there has been proposed a polishing cloth peeling tool comprising a cloth pinching member 120 for pinching the polishing cloth, a cylindrical cloth take-up cylinder 130 having a cloth insertion slit 131 at its peripheral portion, and a ratchet 140 for rotating the cloth take-up cylinder 130 in one direction.
In use, first of all, a part of a peripheral edge of a circular cloth 150 adhered to a turntable is peeled from the turntable, and then the peeled part of the polishing cloth is pinched between an upper member 121 and a lower member 123 of the cloth pinching member 120 and the members 121, 123 are secured together by screws 125. In this case, since three pins 127 are penetrated into the polishing cloth 150 and are inserted into corresponding pin insertion holes 128, the polishing cloth 150 cannot be disengaged from the cloth pinching member 120.
Then, the cloth pinching member 120 is inserted into the cloth take-up cylinder 130 while inserting the pinched polishing cloth 150 into the cloth insertion slit 131.
Then an engagement portion 141 of the ratchet 140 is engaged by a tool engagement portion 133 of the take-up cylinder 130. In this condition, when the ratchet 140 is rotated, the take-up cylinder 130 is rotated in one direction (shown by the arrow H), with the result that the cloth 150 is wound around the take-up cylinder 130.
In this peeling tool, the polishing cloth 150 can be peeled from the turntable easily and positively with a relatively weak force.
However, this peeling tool has the following disadvantages.
(1) If a length of the cloth pinching member 120 is reduced to make the peeling tool compact, as shown in FIG. 7A, since the polishing cloth 150 abuts against the upper and lower screws 125, the polishing cloth 150 cannot be inserted into the cloth pinching member 120 adequately, with the result that the polishing cloth is not pinched by the cloth pinching member completely. Particularly when the cloth pinching member 120 has the pins 127, the polishing cloth 150 does not reach the pins 127.
To avoid such an inconvenience, as shown in FIG. 7B, a tongue 151 is provided at the periphery of the polishing cloth 150 to be pinched by the cloth pinching member 120. In this case, however, the tongue 151 must be provided at the periphery of the polishing cloth 150, with the result that operability is worsened.
(2) It cannot be judged immediately what amount of the polishing cloth 150 pinched by the cloth pinching member 120 is inserted into the cloth pinching member 120, i.e., whether or not the polishing cloth 150 is pinched by the cloth pinching member 120 sufficiently.
(3) In the case where the diameter of the take-up cylinder 130 is reduced to make the peeling tool compact, when the cloth pinching member 120 pinching the cloth 150 is inserted into the take-up cylinder 130, as shown in FIG. 7C, there is a danger of damaging heads of the securing screws 125 by abutting the heads against the inner surface of the cylinder 130. This is true particularly when the securing screws 125 have heads of higher height such as butterfly screws.